decode index checksum too cus why not

also dumps prettier package descriptions to a file now wahoo
I have good priorities

Package.swift

@@ -8,12 +8,14 @@ let package = Package(
   ],
   dependencies: [
     .package(url: "https://github.com/apple/swift-argument-parser", from: "1.5.0"),
+    .package(url: "https://github.com/apple/swift-algorithms", from: "1.2.0"),
     .package(url: "https://github.com/tsolomko/SWCompression", from: "4.8.6"),
   ],
   targets: [
     .target(
       name: "darwin-apk",
       dependencies: [
+        .product(name: "Algorithms", package: "swift-algorithms"),
         .product(name: "SWCompression", package: "SWCompression"),
       ],
       path: "Sources/apk"),